0:00:05 > 0:00:08This is Blue Peter, but mini.
0:00:08 > 0:00:12Expect epic adventures, makes, bakes, badges,
0:00:12 > 0:00:14pets, presenters and your post.
0:00:14 > 0:00:18We've only got five minutes, so get ready for your Blue Peter adventure.
0:00:21 > 0:00:24I'm standing on one of the biggest construction sites in Europe.
0:00:24 > 0:00:26Crossrail is running new train tunnels across the city
0:00:26 > 0:00:28which in itself is pretty impressive,
0:00:28 > 0:00:30but there is so much more to this story.
0:00:30 > 0:00:32And to find out, I've got to go to down there.
0:00:34 > 0:00:37Crossrail is a brand-new underground train line
0:00:37 > 0:00:40being built beneath the streets of central London.
0:00:41 > 0:00:44Look at this, look at the size of the place!
0:00:44 > 0:00:48Costing over £14 billion to construct, this super-sized project
0:00:48 > 0:00:53will tunnel 26 miles across the city at depths of up to 40 metres.
0:00:53 > 0:00:58Now, if you're going to dig this deep and this far in a city this old,
0:00:58 > 0:01:01you're going to find some pretty incredible stuff.
0:01:01 > 0:01:04I don't know, like an ancient burial site, for example.
0:01:04 > 0:01:08Lying directly in the path of the tunnels is a huge graveyard
0:01:08 > 0:01:12near Liverpool Street station, known as the Bedlam Burial Ground.
0:01:12 > 0:01:16This is the final resting place for thousands of Londoners, dating back
0:01:16 > 0:01:20to the 16th century, and includes patients from the Bedlam Hospital.
0:01:20 > 0:01:24So far over 3,000 skeletons have been found, turning this
0:01:24 > 0:01:28building site into one of the UK's biggest archaeological digs.
0:01:28 > 0:01:32What is archaeology? It's much more than just digging stuff up, isn't it?
0:01:32 > 0:01:35Yeah, archaeology is the study of the entire history of humankind,
0:01:35 > 0:01:39so from the very earliest days, when people were making
0:01:39 > 0:01:41the first stone tools,
0:01:41 > 0:01:43right up to a burial ground like this.
0:01:43 > 0:01:47Can you talk me through HOW you dig up a skeleton? What's the process?
0:01:47 > 0:01:49Initially all the modern soils can come off with a machine,
0:01:49 > 0:01:52but once we get down to that level of the first burial
0:01:52 > 0:01:55it's about taking over with very careful hand tools,
0:01:55 > 0:01:57trowels and brushes,
0:01:57 > 0:02:00to carefully pull the soil back away from every individual skeleton.
0:02:00 > 0:02:03Well, obviously this is Blue Peter - I've got my gloves on
0:02:03 > 0:02:04and I'd love to help out if I can.
0:02:04 > 0:02:08Well, let's go and have a look at one of the burials we're excavating
0:02:08 > 0:02:10at the back of the site there, and perhaps you can take
0:02:10 > 0:02:12some of the soil away and put it in a barrow for us.
0:02:12 > 0:02:15- If it's taking soil away, I'm your man. Let's do it.- Let's do it.
0:02:15 > 0:02:19What Jay didn't tell me was just how much earth needs clearing.
0:02:19 > 0:02:22In total, over three million tonnes of the stuff is being removed
0:02:22 > 0:02:24to make room for the new tunnels.
0:02:24 > 0:02:27Yeah, it's a dirty job but someone's got to do it.
0:02:30 > 0:02:31There we go.
0:02:31 > 0:02:34One down, about four million to go.
0:02:37 > 0:02:39Of the 3,000 skeletons the team have already uncovered,
0:02:39 > 0:02:43many were victims of the infamous Plague, or Black Death, that swept
0:02:43 > 0:02:49through London and in 1665 claimed the lives of around 100,000 people.
0:02:49 > 0:02:53This is one of the individual graves that we're excavating.
0:02:53 > 0:02:56Alexa's just cleaning off the final part of the top of the coffin.
0:02:56 > 0:03:00And what is really exciting about it is we've got initials
0:03:00 > 0:03:02appearing on top of the coffin lid.
0:03:02 > 0:03:05What you can see, probably make out, is an R there,
0:03:05 > 0:03:08possibly an O, a C or a G -
0:03:08 > 0:03:11it's been disturbed - and then a number there.
0:03:11 > 0:03:13So this would have recorded the initials of the person
0:03:13 > 0:03:15and the date they were buried.
0:03:16 > 0:03:18What an amazing discovery!
0:03:18 > 0:03:21So while the team continue their work, I went to find out what
0:03:21 > 0:03:25happens to the remains once they've been excavated from the site.
0:03:26 > 0:03:29First of all, the bones need to be carefully cleaned
0:03:29 > 0:03:32and dried, by a team from the Museum of London, before they're sorted
0:03:32 > 0:03:35and prepared for further examination.
0:03:36 > 0:03:40How do you actually go from having trays which are just jumbled up
0:03:40 > 0:03:42pieces of bones and skeleton to putting them all together
0:03:42 > 0:03:44and telling a story?
0:03:44 > 0:03:47Basically you lay the individual out bone by bone
0:03:47 > 0:03:49in anatomical position.
0:03:49 > 0:03:52It's really incredible what an expert like Don
0:03:52 > 0:03:54can tell from studying these bones.
0:03:54 > 0:03:56Well, we can tell they lived
0:03:56 > 0:04:00until they were probably between 20 and 30 years of age.
0:04:00 > 0:04:03We can look at the spine - that tells us that
0:04:03 > 0:04:06they basically walked with a bent back.
0:04:06 > 0:04:08You can tell that they had
0:04:08 > 0:04:12a reasonably soft diet - the teeth aren't that worn.
0:04:12 > 0:04:14So this person didn't eat a lot of sweets?
0:04:14 > 0:04:16Cos the teeth are actually in very good condition.
0:04:16 > 0:04:18We know that most of these individuals weren't really
0:04:18 > 0:04:22that rich, and although sugar HAD been introduced in this period,
0:04:22 > 0:04:24it was quite expensive.
0:04:24 > 0:04:27So whilst the wealthy could tuck into plenty of sugar,
0:04:27 > 0:04:30the poor didn't have quite so much access to it.
0:04:30 > 0:04:32Well, if we move on to our next guy over here.
0:04:32 > 0:04:35That looks like an impact or some kind of injury.
0:04:35 > 0:04:39Something has hit the skull in this area
0:04:39 > 0:04:42and caused the bone to be depressed.
0:04:42 > 0:04:43It's a very serious injury
0:04:43 > 0:04:46and would have required quite extreme force.
0:04:46 > 0:04:48However, we can tell from
0:04:48 > 0:04:50the smooth edges of the bone that
0:04:50 > 0:04:52actually this individual survived.
0:04:52 > 0:04:56- Wow.- It shows that even with quite nasty injuries you could survive,
0:04:56 > 0:04:57even in those days.
0:04:57 > 0:05:00It's quite amazing how you can tell so much from so little, isn't it?
0:05:00 > 0:05:05These are just some of the amazing discoveries being made by the team,
0:05:05 > 0:05:09and they give so many clues about life in London hundreds of years ago.
0:05:09 > 0:05:10When this dig is complete,
0:05:10 > 0:05:12some of their finds will be displayed in the Museum of London
0:05:12 > 0:05:16and the Natural History Museum for everyone to come and see.
0:05:17 > 0:05:20Isn't it fascinating to think that something as new as a modern
0:05:20 > 0:05:23railway station can unearth so much about our past?
0:05:23 > 0:05:25It makes you wonder, doesn't it -
0:05:25 > 0:05:28what other secrets are hidden underneath our feet?
0:05:30 > 0:05:32Join in every Thursday on CBBC.